אימונים Motor Unit Number Estimates In Masters Runners: Use It Or Lose It?

[Mike Bikov]

Med Sci Sports Exerc. 2010 Feb 4. [Epub ahead of print]
Motor Unit Number Estimates In Masters Runners: Use It Or Lose It?

Power GA, Dalton BH, Behm DG, Vandervoort AA, Doherty TJ, Rice CL.

1Canadian Centre for Activity and Aging, School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, Canada 2School of Human Kinetics and Recreation, Memorial University of Newfoundland 3Departments of Clinical Neurological Sciences and Rehabilitation Medicine, The University of Western Ontario, London, ON, Canada 4Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada 5School of Physical Therapy, Faculty of Health Sciences, The University of Western Ontario, Canada.

INTRODUCTION:: A contributing factor to the loss of muscle mass and strength during aging is the reduction in the number of functioning motor units (MUs). It has been shown that life-long physically active older rats have greater numbers of MUs compared with age-matched sedentary controls, suggesting chronic exercise may preserve MU function with advancing age. This has not previously been examined in humans. PURPOSE:: Thus, the purpose was to estimate the number of functioning MUs in the tibialis anterior of master runners (~65 yrs), and compare the values to recreationally active young (~25 yrs), and healthy age matched controls (~65 yrs). METHODS:: Decomposition-enhanced spike-triggered averaging (DE-STA) was used to collect surface and intramuscular electromyography signals during dorsiflexion at 25% of maximum voluntary isometric contraction (MVC). RESULTS:: The estimated number of MUs did not differ between masters runners and young, but motor unit number estimates (MUNE)s were lower in the old (91 +/- 22 MUs) compared to the masters runners (140 +/- 53 MUs) and young (150 +/- 43 MUs). CONCLUSION:: These results demonstrate that lifelong high-intensity physical activity could potentially mitigate the loss of MUs associated with aging well into the seventh decade of life.​

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